![Con11](https://upload.wikimedia.org/wikipedia/commons/3/3c/Con11.jpg)
The Slothouber–Graatsma puzzle is a
packing problem
Packing problems are a class of optimization problems in mathematics that involve attempting to pack objects together into containers. The goal is to either pack a single container as densely as possible or pack all objects using as few conta ...
that calls for packing six 1 × 2 × 2 blocks and three 1 × 1 × 1 blocks into a 3 × 3 × 3 box. The solution to this puzzle is unique (
up to mirror reflections and rotations). It was named after its inventors Jan Slothouber and William Graatsma.
The puzzle is essentially the same if the three 1 × 1 × 1 blocks are left out, so that the task is to pack six 1 × 2 × 2 blocks into a cubic box with volume 27.
Solution
![Slothouber_Graatsma_puzzle](https://upload.wikimedia.org/wikipedia/commons/3/3f/Slothouber_Graatsma_puzzle.svg)
The solution of the Slothouber–Graatsma puzzle is straightforward when one realizes that the three 1 × 1 × 1 blocks (or the three holes) need to be placed along a body diagonal of the box, as each of the 3 x 3 layers in the various directions needs to contain such a unit block. This follows from
parity considerations, because the larger blocks can only fill an even number of the 9 cells in each 3 x 3 layer.
[Elwyn R. Berlekamp, John H. Conway and Richard K. Guy: Winning ways for your mathematical plays, 2nd ed, vol. 4, 2004.]
Variations
The Slothouber–Graatsma puzzle is an example of a cube-packing puzzle using
convex
Convex or convexity may refer to:
Science and technology
* Convex lens, in optics
Mathematics
* Convex set, containing the whole line segment that joins points
** Convex polygon, a polygon which encloses a convex set of points
** Convex polytop ...
polycubes. More general puzzles involving the packing of convex rectangular blocks exist. The best known example is the
Conway puzzle
Conway's puzzle, or blocks-in-a-box, is a packing problem using rectangular blocks, named after its inventor, mathematician John Conway. It calls for packing thirteen 1 × 2 × 4 blocks, one 2 × 2 × 2 block, one 1 × 2 × 2 block, and three 1 × ...
which asks for the packing of eighteen convex rectangular blocks into a 5 x 5 x 5 box. A harder convex rectangular block packing problem is to pack forty-one 1 x 2 x 4 blocks into a 7 x 7 x 7 box (thereby leaving 15 holes); the solution is analogous to the 5x5x5 case, and has three 1x1x5 cuboidal holes in mutually perpendicular directions covering all 7 slices.
See also
*
Soma cube
The Soma cube is a solid dissection puzzle invented by Danish polymath Piet Hein in 1933 during a lecture on quantum mechanics conducted by Werner Heisenberg.
Seven pieces made out of unit cubes must be assembled into a 3×3×3 cube. The pie ...
*
Bedlam cube
The Bedlam cube is a solid dissection puzzle invented by British puzzle expert Bruce Bedlam.
Design
The puzzle consists of thirteen polycubic pieces: twelve pentacubes and one tetracube. The objective is to assemble these pieces into a 4 ...
*
Diabolical cube
The diabolical cube is a three-dimensional dissection puzzle consisting of six polycubes (shapes formed by gluing cubes together face to face) that can be assembled together to form a single 3 × 3 × 3 cube..
The six pieces a ...
References
External links
The Slothouber-Graatsma puzzle in Stewart Coffin's "The Puzzling World of Polyhedral Dissections" William Graatsma and Jan Slothouber: Dutch mathematical art
{{DEFAULTSORT:Slothouber-Graatsma puzzle
Packing problems
Recreational mathematics
Tiling puzzles
Mechanical puzzle cubes